Food preparation environments, such as commercial kitchens, can create air laden with greasy cooking vapor that needs to removed with an air extraction unit. In general, commercial kitchens typically include air extraction units adjacent to cooking areas. An air extraction unit creates a vacuum to remove the cooking vapor from the food preparation area. During the removal, the air can be drawn through an air filtration element remove unwanted odors or substances, and in particular grease, from the air so that grease does not accumulate within the air extraction units. The build up of contaminants, such as grease, within the air extraction unit can create a significant fire hazard. U.S. Code requires the inclusion of listed flame baffles in type I ventilation hoods. Although type I flame baffles can filter some grease, they do not filter grease efficiently and are used to prevent open flames from spreading. Thus, type I flame baffles, by themselves, do not provide adequate grease filtering and can result in significant grease buildup.
The air filtration elements often become quickly soiled depending upon conditions of use and require regular cleaning to maintain an efficient filtering action to provide, e.g. clean air in the workplace. If left for a prolonged period, severe clogging of the filter element may occur, reducing airflow, filtering performance and creating unpleasant working conditions. Badly soiled filters can also release trapped contaminants onto food and food processing surfaces beneath the air filter.
Some air filtration elements can include reusable materials, which are able to be cleaned or reconditioned. Other air filtration elements are disposable. Flame baffle filters have also been used. Nevertheless, cleaning air filtration elements can be quite messy, often inconvenient and deposits may be difficult to remove, requiring harsh or even toxic chemicals. If the air filtration elements are ineffective, the air extraction unit should be cleaned, which is an even more difficult undertaking due to restricted access and the typical location of air extraction units over stoves and/or cooking surfaces. In some circumstances, service companies are contracted to routinely clean air extraction units.
Current air filtration units can include various unnatural fibers and chemicals that may be toxic if ingested or inhaled. U.S. Pat. No. 6,293,983 discloses the use of a wool pre-filter for removing grease from the air, that is used in front of a filter. In order to maintain structural integrity of the pre-filter, the wool is homogenously blended with a synthetic polyester mix, which is melted by application of heat to the coated pre-filter so that the polyester coats the fibers of the pre-filter. The use of a synthetic chemical on the pre-filter is a cause for concern, and a potential hazard.
With the air filtration units' close proximity to cooking surfaces, it is possible that air filtration unit particles may become unknowingly embedded within the food being prepared. Still, to further worsen such a concern, heat from cooking surfaces can release noxious gaseous chemicals from chemicals embedded within the air filtration units. Accordingly, an air filtration unit that is devoid of any toxic or potentially toxic chemicals or particles is desired.